1. Field of the Invention
The present invention relates to speaker systems, and more particularly to a speaker system with a structure which is able to reproduce high fidelity of sound frequencies.
2. Description of Related Art
FIG. 1 is a sectional view of a conventional speaker system wherein the inner space of the sound box 100 forms an air chamber; at the lower part on the front side of the sound box 100 (the right hand side in FIG. 1) an air dissipating hole 102 is formed for connecting the air chamber inside the sound box 100, and a speaker 120 is installed on the upper part.
The speaker 120 comprises a frame 122, and a vibrational cone 124 suspended and mounted on the frame 122. As shown in FIG. 1, a permanent magnet 126 is provided on the backside of the frame 122. A moving coil 128 with coils (not shown) wound thereon is disposed at the end of the cone 124 close to the permanent magnet 126. In addition, a damper 130 is installed between the moving coil 128 and the frame 122. At the instant when a signal of a certain frequency is inputted to the speaker 120, through the coil of the moving coil 128 there flows an electric current corresponding to the frequency so as to make the moving coil 128 become an electromagnet. As such, the permanent magnet 126 pulls the moving coil 128 backwards (i.e., to the left hand side in the Figure), and at the same time, the damper 130 is extended. After this, the magnetic force disappears, the moving coil 128 and the cone 124 immediately bounce forward (i.e., bouncing to the right hand side in the Figure) due to the recovery force of the damper 130, and a sound is generated by the cone 124 compressing air in front.
The aforementioned illustrates the principle of sound generation in a conventional speaker system. The reason why a conventional speaker system has the sound box structure as shown in FIG. 1 is that dampers 130 capable of providing appropriate elastic force in the ranges of frequency response of the speaker 120 were not available. Generally speaking, if the damper 130 is too rigid, it will make the cone 124 bounce back rapidly no matter what frequency of the sound generated by the speaker is, and therefore a low frequency of high fidelity can not be generated; and if the damper 130 is too soft, it will not be able to make the cone 124 bounce back rapidly regardless of the frequency of the sound generated by the speaker, so that the speaker will not be able to generate a high frequency of high fidelity. As such, conventionally a speaker 120 having a relatively soft damper 130 is generally used in a conventional speaker system, wherein the speaker 120 is mounted on the sound box 100. By the action of the permanent magnet 126, in which it pulls the moving coil 128 backwards, the cone 124 compresses the air behind speaker 120 through the holes 132 of the frame 122. Behind the speaker 120 (i.e., inside the sound box 100) instant air pressure (hereunder referred to as “pressurized air cushion”) is generated. Such a pressurized air cushion is utilized to cooperate with the damper 130, enabling the speaker 120 with the relatively soft damper 130 to generate a high frequency of high fidelity. The aforementioned pressurized air cushion is generated instantly, immediately after its performance is completed, it depressurizes through the aforementioned air dissipating holes 120 and disappears.
In theory, in the configuration of the above mentioned speaker system, when the speaker 120 generates a sound of different sound frequency, there must be a different corresponding pressure behind it, so as to enable the speaker 120 to generate a sound frequency of high fidelity in each frequency range of the frequency response. However, it is not easy to generate different pressurized air cushion in one specific air chamber inside sound box 100. Therefore the conventional speaker system as constructed in FIG. 1 still cannot allow the speaker 120 to generate a sound frequency of high fidelity in each frequency range of the frequency response.
Furthermore, even if pressurized air cushions of different pressures can be generated within a single sound box 100, it is difficult for the air dissipating hole 102 of a fixed diameter to make the pressurized air cushions of different pressures to disappear instantly, therefore it is possible for the next air cushion to be generated already prior to the disappearance of the previous air cushion. In such a situation the air cushions interfering with but not independent from each other; moreover, it is not only incapable of improving the speaker's ability to reproduce the original sound, but possible that the sound quality of the speaker is deteriorated.
This invention has been developed to resolve the above mentioned problems and its objective is to provide a speaker system that is capable of generating behind its speaker pressurized air cushions corresponding to each frequency range of the frequency response of the speaker, so as to have an appropriate as well as independent air cushion in cooperation with the speaker in each frequency range of frequency response of the speaker, and therefore capable of generating a sound frequency closer to that of the inputted sound signal.